This invention relates in general to mold and die supporting mechanisms and in particular to a quick change holder for releasably supporting a plurality of rubber oil seal mold inserts in a power press machine.
Annular rubber oil seals are presently manufactured by compression molding a quantity of uncured rubber material between upper and lower cooperating mold halves, referred to as mold inserts. Initially, the upper mold insert is secured to the movable ram of a conventional power press machine, while the lower mold insert is secured to the bolster thereof. Both of the mold inserts are heated to a predetermined temperature, for a purpose which will be explained below. To form the oil seal, the uncured rubber material is disposed between the upper and lower mold inserts. The ram is then lowered toward the bolster such that the upper mold insert is moved adjacent to the lower mold insert, thereby compressing he rubber material therebetween. The mold inserts are shaped such that the rubber material takes a desired configuration for the oil seal when compressed. The combined heat and pressure exerted by the mold inserts against the rubber material causes it to cure after a period of time. After the rubber material has hardened, the ram and the upper mold insert are raised, thereby permitting the newly formed oil seal to be removed. A conventional stripper plate may be used to assist in removing the seal from the mold inserts.
In order to increase the efficiency of the above described process, it is known to mount a plurality of upper and lower mold inserts within the power press machine such that a plurality of oil seals are simultaneously formed on each stroke of the ram. To accomplish this, upper and lower mold plates are provided to secure the pluralities of upper and lower mold inserts respectively to the ram and the bolster of the power press machine. The upper mold plate is formed from a generally flat piece of metal having a plurality of apertures formed therethrough, one for each of the upper mold inserts to be retained therein. A counterbore is formed about each of the apertures in the upper surface of the upper mold plate so as to define a recessed, reduced diameter annular shoulder within each aperture.
Each of the mold inserts is generally cylindrical in shape, having an enlarged diameter annular collar formed circumferentially about the upper end thereof. The upper mold inserts are installed in the upper mold plate by lowering them through the upper surface into the apertures until the collars engage the shoulders in the counterbores. The upper mold plate, carrying all of the upper mold inserts which have been inserted in this manner, is then attached to the ram of the power press machine by any conventional means. The lower mold plate and the lower mold inserts are installed in a similar fashion, except that the counterbores in the lower mold plate are formed in the lower surface thereof and the lower mold insert collars are formed about the lower ends thereof.
Although this structure has increased the overall efficiency of he oil seal formation process, it has also been found to be somewhat cumbersome when it is desired to remove some or all of the mold inserts from the power press machine. Such removal may be necessary to replace all of the installed mold inserts with differently shaped mold inserts to permit the formation of oil seals having a different configuration. Alternatively, it may be necessary to remove only a single pair of the inserts for cleaning, while the other pairs continue to be used. In any event, the structure described above does not lend itself to readily removing any the mold inserts from the mold plates. Such removal requires the detachment of, for example, the upper mold plate from the ram so that the upper mold inserts can be removed by raising them upwardly out of the apertures. This can be a time consuming and awkward process, especially if the mold inserts are large and heavy. Indeed, in some instances, a motorized lift vehicle is required to support the very heavy mold plates during this removal process. Additionally, once the desired mold inserts are removed, the mold plates have to be precisely re-positioned within the power press machine before re-attachment. This repetition of the positioning process for each removal of the mold inserts causes further delay and inconvenience.